In some cases, nand_do_{read,write}_ops is passed with unaligned
ops->datbuf. Drivers using DMA will be unhappy about unaligned
buffer.
The new struct member, buf_align, represents the minimum alignment
the driver require for the buffer. If the buffer passed from the
upper MTD layer does not have enough alignment, nand_do_*_ops will
use bufpoi.
Signed-off-by: Masahiro Yamada <yamada.masah...@socionext.com>
---
I was hit by this problem when I ran
# mount -t jffs2 /dev/mtdblock* /mnt
The buffer passed to nand_do_*_ops has 4 byte offset.
The Denali IP cannot do DMA to/from this buffer because it
requires 16 byte alignment for DMA.
Changes in v3:
- Newly added
Changes in v2: None
drivers/mtd/nand/nand_base.c | 12 ++++++++----
include/linux/mtd/nand.h | 2 ++
2 files changed, 10 insertions(+), 4 deletions(-)
diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
index e9d3195..b528ffa 100644
--- a/drivers/mtd/nand/nand_base.c
+++ b/drivers/mtd/nand/nand_base.c
@@ -1953,9 +1953,10 @@ static int nand_do_read_ops(struct mtd_info *mtd, loff_t
from,
if (!aligned)
use_bufpoi = 1;
- else if (chip->options & NAND_USE_BOUNCE_BUFFER)
- use_bufpoi = !virt_addr_valid(buf);
- else
+ else if (chip->options & NAND_USE_BOUNCE_BUFFER) {
+ use_bufpoi = !virt_addr_valid(buf) ||
+ !IS_ALIGNED((unsigned long)buf, chip->buf_align);
+ } else
use_bufpoi = 0;
/* Is the current page in the buffer? */
@@ -2810,7 +2811,8 @@ static int nand_do_write_ops(struct mtd_info *mtd, loff_t
to,
if (part_pagewr)
use_bufpoi = 1;
else if (chip->options & NAND_USE_BOUNCE_BUFFER)
- use_bufpoi = !virt_addr_valid(buf);
+ use_bufpoi = !virt_addr_valid(buf) ||
+ !IS_ALIGNED((unsigned long)buf, chip->buf_align);
else
use_bufpoi = 0;
@@ -3426,6 +3428,8 @@ static void nand_set_defaults(struct nand_chip *chip, int
busw)
nand_hw_control_init(chip->controller);
}
+ if (!chip->buf_align)
+ chip->buf_align = 1;
}
/* Sanitize ONFI strings so we can safely print them */
diff --git a/include/linux/mtd/nand.h b/include/linux/mtd/nand.h
index 69cccd1..2ae781e 100644
--- a/include/linux/mtd/nand.h
+++ b/include/linux/mtd/nand.h
@@ -750,6 +750,7 @@ nand_get_sdr_timings(const struct nand_data_interface *conf)
* setting the read-retry mode. Mostly needed for MLC NAND.
* @ecc: [BOARDSPECIFIC] ECC control structure
* @buffers: buffer structure for read/write
+ * @buf_align: minimum buffer alignment required by a platform
* @hwcontrol: platform-specific hardware control structure
* @erase: [REPLACEABLE] erase function
* @scan_bbt: [REPLACEABLE] function to scan bad block table
@@ -901,6 +902,7 @@ struct nand_chip {
struct nand_ecc_ctrl ecc;
struct nand_buffers *buffers;
+ unsigned long buf_align;
struct nand_hw_control hwcontrol;
uint8_t *bbt;
--
2.7.4
